U.S. patent application number 17/606529 was filed with the patent office on 2022-07-07 for beam selection method and apparatus.
The applicant listed for this patent is Huawei Technologies Co., Ltd.. Invention is credited to Yong Cheng, Cen Ling, Bin Liu, Xiaoyong Yu.
Application Number | 20220216907 17/606529 |
Document ID | / |
Family ID | |
Filed Date | 2022-07-07 |
United States Patent
Application |
20220216907 |
Kind Code |
A1 |
Ling; Cen ; et al. |
July 7, 2022 |
Beam Selection Method and Apparatus
Abstract
A beam selection method includes determining, by a terminal, a
first angular power spectrum of a low frequency channel transmitted
between the terminal and an access network device, determining, by
the terminal, a first high frequency beam scanning range based on
the first angular power spectrum, and scanning, by the terminal,
the first high frequency beam scanning range for a high frequency
beam of the access network device.
Inventors: |
Ling; Cen; (Shanghai,
CN) ; Yu; Xiaoyong; (Shanghai, CN) ; Cheng;
Yong; (Shenzhen, CN) ; Liu; Bin; (Shenzhen,
CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Huawei Technologies Co., Ltd. |
Shenzhen |
|
CN |
|
|
Appl. No.: |
17/606529 |
Filed: |
April 20, 2020 |
PCT Filed: |
April 20, 2020 |
PCT NO: |
PCT/CN2020/085513 |
371 Date: |
October 26, 2021 |
International
Class: |
H04B 7/08 20060101
H04B007/08 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 26, 2019 |
CN |
2019 10346557.3 |
Claims
1. An angular power spectrum method implemented by a terminal,
wherein the method comprises: determining a first angular power
spectrum of a first low frequency channel transmitted between the
terminal and an access network device; determining a first high
frequency beam scanning range based on the first angular power
spectrum; and scanning the first high frequency beam scanning range
for a high frequency beam of the access network device.
2. The method of claim 1, wherein further comprising: calculating a
peak-to-average ratio of the first low frequency channel based on
the first angular power spectrum; determining, based on the
peak-to-average ratio and a correspondence between the
peak-to-average ratio and a high frequency beam region range, a
first region range corresponding to the peak-to-average ratio; and
further determining the first high frequency beam scanning range
based on the first region range and an angle of a second low
frequency channel, wherein a peak value of the second low frequency
channel is at a first threshold that is preset.
3. The method of claim 1, wherein the first angular power spectrum
is a direction of arrival (DOA) power spectrum or a direction of
departure (DOD) power spectrum.
4. The method of claim 1, wherein before determining the first high
frequency beam scanning range, the method further comprises:
determining a rotation angle of the terminal; and correcting the
first angle power spectrum based on the rotation angle.
5. The method of claim 1, wherein after determining the first
angular power spectrum, the method further comprises determining a
second angular power spectrum of the first low frequency channel
when the terminal moves and a moving distance of the terminal is
greater than a channel correlation distance, wherein the channel
correlation distance is based on a channel scenario in which the
terminal is currently located, and wherein the channel scenario is
based on the first angular power spectrum.
6. The method of claim 5, further comprising: determining, based on
the second angular power spectrum, a second high frequency beam
scanning range; and scanning the second high frequency beam
scanning range for the high frequency beam.
7. The method of claim 1, further comprising: making a
determination that a whitelist at the terminal comprises
information about the access network device that supports beam
scanning using a channel characteristic of the first low frequency
channel; and further determining, in response to the determination,
the first angular power spectrum.
8. The method of claim 1, further comprising: making a
determination that first information about the access network
device is not comprised in a blacklist at the terminal; and further
determining, in response to the determination, the first angular
power spectrum.
9. The method of claim 1, further comprising selecting a candidate
beam based on the first angular power spectrum.
10. A communications apparatus, wherein the communications
apparatus is a terminal, a functional component of the terminal, or
a chip in the terminal, and wherein the communications apparatus
comprises: a memory configured to store instructions; and a
processor coupled to the memory, wherein the instructions cause the
processor to be configured to: determine a first angular power
spectrum of a first low frequency channel transmitted between the
terminal and an access network device; determine a first high
frequency beam scanning range based on the first angular power
spectrum; and scan the first high frequency beam scanning range for
a high frequency beam of the access network device.
11. The communications apparatus of claim 10, wherein the
instructions further cause the processor to be configured to:
calculate a peak-to-average ratio of the first low frequency
channel based on the first angular power spectrum; determine, based
on the peak-to-average ratio and a correspondence between the
peak-to-average ratio and a high frequency beam region range, a
first region range corresponding to the peak-to-average ratio; and
determine the first high frequency beam scanning range based on the
first region range and an angle of a second low frequency channel,
wherein a peak value of the second low frequency channel is at a
first threshold that is preset.
12. The communications apparatus of claim 10, wherein the first
angular power spectrum is a direction of arrival (DOA) power
spectrum or a direction of departure (DOD) power spectrum.
13. The communications apparatus of claim 10, wherein before
determining the first high frequency beam scanning range, the
instructions further cause the processor to be configured to:
determine a rotation angle of the terminal; and correct the first
angular power spectrum based on the rotation angle.
14. The communications apparatus of claim 10, wherein after
determining the first angular power spectrum, the instructions
further cause the processor to be configured to determine a second
angular power spectrum of the first low frequency channel when the
terminal moves and a moving distance of the terminal is greater
than a channel correlation distance, wherein the channel
correlation distance is based on a channel scenario in which the
terminal is currently located, and wherein the channel scenario is
based on the first angular power spectrum.
15. The communications apparatus of claim 14, wherein the
instructions further cause the processor to be configured to:
determine a second high frequency beam scanning range based on a
re-determined angular power spectrum; and scan the second high
frequency beam scanning range for the high frequency beam.
16. The communications apparatus of claim 10, wherein the
instructions further cause the processor to be configured to: make
a determination that a whitelist of the communications apparatus
comprises information about the access network device that supports
beam scanning using a channel characteristic of the first low
frequency channel; and further determine, based on the
determination, the first angular power spectrum.
17. The communications apparatus of claim 10, wherein the
instructions further cause the processor to be configured to: make
a determination that information about the access network device is
not comprised in a blacklist of the communications apparatus; and
determine, in response to the determination, the first angular
power spectrum.
18. The communications apparatus of claim 10, wherein the
instructions further cause the processor to be configured to select
a candidate beam based on the first angular power spectrum.
19. (canceled)
20. A computer program product comprising computer-executable
instructions that are stored on a non-transitory computer-readable
storage medium and that, when executed by a processor, cause an
apparatus to: determine a first angular power spectrum of a first
low frequency channel transmitted between the terminal and an
access network device; determine a first high frequency beam
scanning range based on the first angular power spectrum; and scan
the first high frequency beam scanning range for a high frequency
beam of the access network device.
21.-22. (canceled)
23. The computer program product of claim 20, wherein the
computer-executable instructions further cause the apparatus to:
calculate a peak-to-average ratio of the first low frequency
channel based on the first angular power spectrum; determine, based
on the peak-to-average ratio and a correspondence between the
peak-to-average ratio and a high frequency beam region range, a
first region range corresponding to the peak-to-average ratio; and
further determine the first high frequency beam scanning range
based on the first region range and an angle of a second low
frequency channel, wherein a peak value of the second low frequency
channel is at a first threshold that is preset.
Description
[0001] This application claims priority to Chinese Patent
Application No. 201910346557.3, filed with the China National
Intellectual Property Administration on Apr. 26, 2019 and entitled
"BEAM SELECTION METHOD AND APPARATUS", which is incorporated herein
by reference in its entirety.
TECHNICAL FIELD
[0002] Embodiments of this application relate to the field of
communications technologies, and in particular, to a beam selection
method and an apparatus.
BACKGROUND
[0003] With development of communications technologies, a carrier
aggregation (carrier aggregation, CA) manner based on high and low
frequency coordination becomes an inevitable development trend of a
future new radio (new radio, NR) network. For example, in the NR
network, a terminal and a base station may transmit a signal on a
low frequency band carrier, and may also transmit a signal on a
millimeter wave frequency band. However, because the millimeter
wave frequency band is featured in relatively high attenuation, a
relatively weak diffraction capability, and the like, problems such
as significant signal fading and an increased path loss are easily
caused by transmitting the signal on the millimeter wave frequency
band. To avoid these problems, the base station and the terminal
may transmit a signal by using a high frequency beamforming
technology. For example, the terminal (or the base station) may
perform high frequency beamforming on a to-be-transmitted signal by
using an antenna array, to form a precise narrow high frequency
beam, and then send the high frequency beam to the base station (or
the terminal). The base station (or the terminal) may form a
precise narrow high frequency beam by using the high frequency
beamforming technology to receive a signal sent by the terminal (or
the base station). In this way, channel quality of a transmission
channel between the base station and the terminal can be improved,
and the problems such as the significant signal fading and the
increased path loss caused by communication on the millimeter wave
frequency band can be overcome.
[0004] A plurality of high frequency beams may be formed between
the base station and the terminal, and signal quality of the high
frequency beams may be different. Currently, a high frequency beam
with optimal signal quality between the base station and the
terminal is obtained in the 3rd generation partnership project (3rd
generation partnership project, 3GPP) NR protocol in phases P1 to
P3 in which stage-by-stage scanning is performed to first obtain a
wide beam and then obtain a narrow beam. Phase P1: Obtain wide
beams of the base station and the terminal. Phase P2: Obtain a
narrow beam of the base station. Phase P3: Obtain a narrow beam of
the terminal. For example, 15 wide beams are configured on the base
station side, and each wide beam includes 10 narrow beams. The
terminal side may first find several beams from a total set of 256
beams, then perform global coarse scanning for seven wide beams,
and perform neighborhood tracking for seven narrow beams, to select
a globally optimal high frequency beam. In this case, 15.times.7
times of scanning are required in the phase P1, 10 times of
scanning are required in the phase P2, and 7 times of scanning are
required in the phase P3.
[0005] It can be learned from the foregoing descriptions that three
processing processes, that is, the phases P1 to P3, need to be
performed during existing beam selection. Using beam search and
reference signal feedback in each phase requires extremely high
signaling overheads, a high delay, and high power consumption.
SUMMARY
[0006] Embodiments of this application provide a beam selection
method and an apparatus, to resolve problems of high signaling
overheads and a relatively long scanning process time in an
existing beam scanning manner.
[0007] To achieve the foregoing objective, the following technical
solutions are used in the embodiments of this application.
[0008] According to a first aspect, an embodiment of this
application provides a beam selection method, and the method may
include: A terminal determines a first angular power spectrum of a
low frequency channel transmitted between the terminal and an
access network device, determines a first high frequency beam
scanning range based on the first angular power spectrum, and scans
the first high frequency beam scanning range for a high frequency
beam sent by the access network device.
[0009] Based on the method according to the first aspect, when
scanning the high frequency beam delivered by the access network
device, the terminal may determine the first high frequency beam
scanning range based on the angular power spectrum of the low
frequency channel transmitted between the terminal and the access
network device, and scan, in the determined first high frequency
beam scanning range, the high frequency beam sent by the access
network device. In this way, the terminal may scan the high
frequency beam in a specific range, and does not need to scan the
high frequency beam in a large range (for example, an
omnidirectional range) in three phases P1 to P3 as in the
conventional technology. Compared with the conventional technology,
the method in the first aspect reduces a scanning time, and in
addition, a quantity of scanning times is reduced, and signaling
interaction with the access network device does not need to be
performed for a plurality of times, thereby reducing signaling
overheads.
[0010] With reference to the first aspect, in a first embodiment of
the first aspect, that the terminal determines a first high
frequency beam scanning range based on the first angular power
spectrum includes: The terminal calculates a peak-to-average ratio
of the low frequency channel based on the first angular power
spectrum, determines, based on the peak-to-average ratio of the low
frequency channel and a correspondence between the peak-to-average
ratio and a high frequency beam region range, a first region range
corresponding to the peak-to-average ratio of the low frequency
channel, and determines the first high frequency beam scanning
range based on the first region range and an angle of a low
frequency channel whose peak value is a first threshold.
[0011] Based on the first embodiment of the first aspect, the
terminal may determine the first high frequency beam scanning range
based on the peak-to-average ratio of the low frequency channel,
for example, determine the peak-to-average ratio of the low
frequency channel based on the angular power spectrum, obtain,
based on the peak-to-average ratio of the low frequency channel and
the preset correspondence between the peak-to-average ratio and the
high frequency beam region range, the first region range
corresponding to the peak-to-average ratio of the low frequency
channel, and determine the first high frequency beam scanning range
based on the first region range and the angle of the low frequency
channel whose peak value is the first threshold. This process is
simple and easy.
[0012] With reference to the first aspect or the first embodiment
of the first aspect, the first angular power spectrum is a
direction of arrival DOA power spectrum or a direction of departure
DOD power spectrum. In this way, when scanning for the high
frequency beam sent by the access network device, the terminal may
determine the first high frequency beam scanning range based on the
DOA power spectrum that is of the low frequency channel and that is
sent by the access network device to the terminal, and determine,
in a case of channel reciprocity, the first high frequency beam
scanning range based on the DOD power spectrum that is of the low
frequency channel and that is sent by the terminal to the access
network device. Determining manners are flexible and diverse.
[0013] With reference to the first aspect or any embodiment of the
first aspect, in a third embodiment of the first aspect, before the
terminal determines a first high frequency beam scanning range
based on the first angular power spectrum, the method further
includes: The terminal determines a rotation angle of the terminal;
and the terminal corrects the first angle power spectrum based on
the rotation angle of the terminal.
[0014] Based on the third embodiment of the first aspect, when the
terminal rotates, the first angular power spectrum may be corrected
in time based on the rotation angle of the terminal, and the first
high frequency beam scanning range may be determined based on the
corrected angular power spectrum, to ensure accuracy of the
determined first high frequency beam scanning range.
[0015] With reference to the first aspect or any embodiment of the
first aspect, in a fourth embodiment of the first aspect, after the
terminal determines a first angular power spectrum, the method
further includes: When the terminal moves, and a moving distance of
the terminal is greater than a channel correlation distance, the
terminal re-determines, after the terminal moves, an angular power
spectrum of the low frequency channel transmitted between the
terminal and the access network device, for example, determines a
second angular power spectrum of the low frequency channel
transmitted between the terminal and the access network device. The
channel correlation distance is determined based on a channel
scenario in which the terminal is currently located, and the
channel scenario in which the terminal is currently located is
determined based on the first angular power spectrum.
[0016] Based on the fourth embodiment of the first aspect, when the
terminal moves, and a moving amplitude is relatively large, the
angular power spectrum of the low frequency channel transmitted
between the terminal and the access network device may be
re-determined, to ensure that the determined angular power spectrum
conforms to a channel characteristic of the low frequency channel
between the terminal and the access network device after the
terminal moves.
[0017] With reference to the fourth embodiment of the first aspect,
in a fifth embodiment of the first aspect, the method further
includes: The terminal determines, based on the second angular
power spectrum, a second high frequency beam scanning range, and
scans the second high frequency beam scanning range for the high
frequency beam sent by the access network device.
[0018] Based on the fifth embodiment of the first aspect, when the
terminal moves, the terminal may determine the second high
frequency beam scanning range based on the re-determined second
angular power spectrum, and scan the determined second high
frequency beam scanning range for the high frequency beam sent by
the access network device, so as to improve scanning accuracy.
[0019] With reference to the first aspect or any embodiment of the
first aspect, in a sixth embodiment of the first aspect, that a
terminal determines a first angular power spectrum of a low
frequency channel transmitted between the terminal and an access
network device includes: When a whitelist includes information
about the access network device, the terminal determines the first
angular power spectrum of the low frequency channel transmitted
between the terminal and the access network device, where the
whitelist includes the information about the access network device
that supports beam scanning by using a channel characteristic of
the low frequency channel.
[0020] Based on the sixth embodiment of the first aspect, the
method in this embodiment of this application may be used to
determine the first high frequency beam scanning range by using the
channel characteristic of the low frequency channel only when the
access network device supports the information about the access
network device that performs beam scanning by using the channel
characteristic of the low frequency channel. The terminal scans the
determined first high frequency beam scanning range for the high
frequency beam, so that the terminal does not need to attempt to
scan the high frequency beam by using the conventional technology,
thereby reducing complexity of scanning the high frequency beam by
the terminal.
[0021] With reference to any one of the first aspect to the fifth
embodiment of the first aspect, in a seventh embodiment of the
first aspect, that a terminal determines a first angular power
spectrum of a low frequency channel transmitted between the
terminal and an access network device includes: When the terminal
determines that information about the access network device is not
included in a blacklist, the terminal determines the first angular
power spectrum of the low frequency channel transmitted between the
terminal and the access network device, where the blacklist
includes the information about the access network device that does
not support beam scanning by using a channel characteristic of the
low frequency channel.
[0022] Based on the seventh embodiment of the first aspect, when
the access network device is not included in the blacklist, the
method in this embodiment of this application may be used to
determine the first high frequency beam scanning range by using the
channel characteristic of the low frequency channel, and scan the
determined first high frequency beam scanning range for the high
frequency beam. That is, when scanning the high frequency beam, the
terminal preferentially uses the method described in this
embodiment of this application. Further, if no high frequency beam
is found by using the method in this embodiment of this
application, the terminal attempts to scan for the high frequency
beam by using the conventional technology, thereby reducing
complexity of scanning the high frequency beam by the terminal.
[0023] With reference to the first aspect or any embodiment of the
first aspect, in an eighth embodiment of the first aspect, the
method further includes: The terminal selects a candidate beam
based on the first angular power spectrum.
[0024] Based on the seventh embodiment of the first aspect, the
terminal may select the candidate beam, so that when the high
frequency beam is not successfully found in the determined first
high frequency beam scanning range, the terminal attempts to scan,
at a location of the candidate beam, the high frequency beam sent
by the access network device.
[0025] According to a second aspect, this application provides a
communications apparatus. The communications apparatus may be a
terminal, a chip in the terminal, or a system-on-a-chip; or may be
a functional module that is in the terminal and that is configured
to implement the method according to any one of the first aspect or
the possible designs of the first aspect. The communications
apparatus may implement functions performed by the terminal in the
first aspect or any embodiment of the first aspect, and the
functions may be implemented by executing corresponding software by
hardware. The hardware or the software includes one or more modules
corresponding to the functions. For example, the communications
apparatus may include a determining unit and a scanning unit.
[0026] The determining unit is configured to: determine a first
angular power spectrum of a low frequency channel transmitted
between the terminal and an access network device, and determine a
first high frequency beam scanning range based on the first angular
power spectrum.
[0027] The scanning unit is configured to scan the first high
frequency beam scanning range for a high frequency beam sent by the
access network device.
[0028] Based on the method according to the second aspect, when
scanning the high frequency beam delivered by the access network
device, the communications apparatus may determine the first high
frequency beam scanning range based on the first angular power
spectrum of the low frequency channel transmitted between the
terminal and the access network device, and scan the first high
frequency beam scanning range for the high frequency beam sent by
the access network device. In this way, the high frequency beam may
be scanned for in a specific range, and the high frequency beam
does not need to be scanned for in a large range (for example, an
omnidirectional range) by using three phases P1 to P3 as in the
conventional technology. Compared with the conventional technology,
the method in the second aspect reduces a scanning time, and in
addition, a quantity of scanning times is reduced, and signaling
interaction with the access network device does not need to be
performed for a plurality of times, thereby reducing signaling
overheads.
[0029] With reference to the second aspect, in a first embodiment
of the second aspect, the determining unit is specifically
configured to: calculate a peak-to-average ratio of the low
frequency channel based on the first angular power spectrum;
determine, based on the peak-to-average ratio of the low frequency
channel and a correspondence between the peak-to-average ratio and
a high frequency beam region range, a first region range
corresponding to the peak-to-average ratio of the low frequency
channel; and determine the first high frequency beam scanning range
based on the first region range and an angle of a low frequency
channel whose peak value is a first threshold.
[0030] Based on the first embodiment of the second aspect, the
first high frequency beam scanning range may be determined based on
the peak-to-average ratio of the low frequency channel, for
example, the peak-to-average ratio of the low frequency channel may
be determine based on the angular power spectrum, the first region
range corresponding to the peak-to-average ratio of the low
frequency channel may be obtained based on the peak-to-average
ratio of the low frequency channel and the preset correspondence
between the peak-to-average ratio and the high frequency beam
region range, and the first high frequency beam scanning range is
determined based on the first region range and the angle of the low
frequency channel whose peak value is the first threshold. This
process is simple and easy.
[0031] With reference to the second aspect or the first embodiment
of the second aspect, the first angular power spectrum is a
direction of arrival DOA power spectrum or a direction of departure
DOD power spectrum. In this way, when scanning for the high
frequency beam sent by the access network device, the terminal may
determine the first high frequency beam scanning range based on the
DOA power spectrum that is of the low frequency channel and that is
sent by the access network device to the terminal, and in a case of
channel reciprocity, determine the first high frequency beam
scanning range based on the DOD power spectrum that is of the low
frequency channel and that is sent by the terminal to the access
network device. Determining manners are flexible and diverse.
[0032] With reference to the second aspect or any embodiment of the
second aspect, in a third embodiment of the second aspect, the
determining unit is further configured to: before the determining
unit determines the first high frequency beam scanning range based
on the first angular power spectrum, determine a rotation angle of
the terminal, and correct the first angular power spectrum based on
the rotation angle of the terminal.
[0033] Based on the third embodiment of the second aspect, when the
terminal rotates, the first angular power spectrum may be corrected
in time based on the rotation angle of the terminal, and the first
high frequency beam scanning range may be determined based on the
corrected angular power spectrum, so as to ensure accuracy of the
determined first high frequency beam scanning range.
[0034] With reference to the second aspect or any embodiment of the
second aspect, in a fourth embodiment of the second aspect, the
determining unit is further configured to: after determining the
first angular power spectrum, when the terminal moves, and a moving
distance of the terminal is greater than a channel correlation
distance, re-determine, after the terminal moves, an angular power
spectrum of the low frequency channel transmitted between the
terminal and the access network device, for example, determine a
second angular power spectrum of the low frequency channel
transmitted between the terminal and the access network device is
determined. The channel correlation distance is determined based on
a channel scenario in which the terminal is currently located, and
the channel scenario in which the terminal is currently located is
determined based on the first angular power spectrum.
[0035] Based on the fourth embodiment of the second aspect, when
the terminal moves, and a moving amplitude is relatively large, the
angular power spectrum of the low frequency channel transmitted
between the terminal and the access network device may be
re-determined, to ensure that the determined angular power spectrum
conforms to a channel characteristic of the low frequency channel
between the terminal and the access network device after the
terminal moves.
[0036] With reference to the fourth embodiment of the second
aspect, in a fifth embodiment of the second aspect, the determining
unit is further configured to determine a second high frequency
beam scanning range based on the second angular power spectrum; and
the scanning unit is further configured to scan the second high
frequency beam scanning range for the high frequency beam sent by
the access network device.
[0037] Based on the fifth embodiment of the second aspect, when the
terminal moves, the terminal may determine the second high
frequency beam scanning range based on the re-determined second
angular power spectrum, and scan the determined second high
frequency beam scanning range for the high frequency beam sent by
the access network device, so as to improve scanning accuracy.
[0038] With reference to the second aspect or any embodiment of the
second aspect, in a sixth embodiment of the second aspect, the
determining unit is specifically configured to: when a whitelist
includes information about the access network device, determine the
first angular power spectrum of the low frequency channel
transmitted between the terminal and the access network device,
where the whitelist includes the information about the access
network device that supports beam scanning by using a channel
characteristic of the low frequency channel.
[0039] Based on the sixth embodiment of the second aspect, the
method in this embodiment of this application may be used to
determine the first high frequency beam scanning range by using the
channel characteristic of the low frequency channel only when the
access network device supports the information about the access
network device that performs beam scanning by using the channel
characteristic of the low frequency channel. The terminal scans the
determined first high frequency beam scanning range for the high
frequency beam, so that the terminal does not need to attempt to
scan the high frequency beam by using the conventional technology,
thereby reducing complexity of scanning the high frequency beam by
the terminal.
[0040] With reference to any one of the second aspect to the fifth
embodiment of the second aspect, in a seventh embodiment of the
second aspect, the determining unit is specifically configured to:
when the terminal determines that information about the access
network device is not included in a blacklist, determine the first
angular power spectrum of the low frequency channel transmitted
between the terminal and the access network device, where the
blacklist includes the information about the access network device
that does not support beam scanning by using a channel
characteristic of the low frequency channel.
[0041] Based on the seventh embodiment of the second aspect, when
the access network device is not included in the blacklist, the
method in this embodiment of this application may be used to
determine the first high frequency beam scanning range by using the
channel characteristic of the low frequency channel, and scan the
determined first high frequency beam scanning range for the high
frequency beam. That is, when scanning the high frequency beam, the
terminal preferentially uses the method described in this
embodiment of this application. Further, if no high frequency beam
is found by using the method in this embodiment of this
application, the terminal attempts to scan for the high frequency
beam by using the conventional technology, thereby reducing
complexity of scanning the high frequency beam by the terminal.
[0042] With reference to the second aspect or any embodiment of the
second aspect, in an eighth embodiment of the second aspect, the
communications apparatus further includes: a selection unit,
configured to select a candidate beam based on the first angular
power spectrum.
[0043] Based on the seventh embodiment of the second aspect, the
terminal may select the candidate beam, so that when the high
frequency beam is not successfully found in the determined first
high frequency beam scanning range, the terminal attempts to scan a
location of the candidate beam for the high frequency beam sent by
the access network device.
[0044] According to a third aspect, a communications apparatus is
provided. The communications apparatus may be a terminal, a chip in
the terminal, or a system-on-a-chip. The communications apparatus
may implement functions performed by the terminal in any one of the
first aspect or the embodiments of the first aspect, and the
functions may be implemented by hardware. For example, in a
possible design, the communications apparatus may include a
processor and a communications interface.
[0045] The processor is configured to: determine a first angular
power spectrum of a low frequency channel transmitted between the
terminal and an access network device, and determine a first high
frequency beam scanning range based on the first angular power
spectrum; and
[0046] scan the first high frequency beam scanning range for a high
frequency beam sent by the access network device.
[0047] For a specific implementation of the communications
apparatus, refer to behavior and functions of the terminal in the
beam selection method according to any one of the first aspect or
the possible designs of the first aspect. Details are not repeated
herein again. Therefore, the provided communications apparatus can
achieve same beneficial effects as any one of the first aspect or
the possible designs of the first aspect.
[0048] In still another possible design, in the third aspect, the
communications apparatus may further include a memory. The memory
is configured to store computer-executable instructions and data
that are necessary for the communications apparatus. When the
communications apparatus runs, the processor executes the
computer-executable instructions stored in the memory, so that the
communications apparatus performs the beam selection method
according to any one of the first aspect or the possible designs of
the first aspect.
[0049] According to a fourth aspect, a computer-readable storage
medium is provided. The computer-readable storage medium may be a
readable non-volatile storage medium. The computer-readable storage
medium stores instructions. When the instructions are run on a
computer, the computer is enabled to perform the beam selection
method according to any one of the first aspect or the possible
designs of the foregoing aspects.
[0050] According to a fifth aspect, a computer program product
including instructions is provided. When the computer program
product runs on a computer, the computer is enabled to perform the
beam selection method according to any one of the first aspect or
the possible designs of the foregoing aspects.
[0051] According to a sixth aspect, a communications apparatus is
provided. The communications apparatus may be a terminal, a chip in
the terminal, or a system-on-a-chip. The communications apparatus
includes one or more processors and one or more memories. The one
or more memories are coupled to the one or more processors, and the
one or more memories are configured to store computer program code.
The computer program code includes computer instructions, and when
the one or more processors execute the computer instructions, the
communications apparatus is enabled to perform the beam selection
method according to any one of the first aspect or the possible
designs of the first aspect.
[0052] For technical effects achieved by any one of the designs of
the third aspect to the sixth aspect, refer to the technical
effects achieved by any one of the first aspect or the possible
designs of the first aspect. Details are not described again.
[0053] According to a seventh aspect, an embodiment of this
application provides a beam selection method system. The system may
include the terminal and the access network device according to any
one of the second aspect to the sixth aspect.
BRIEF DESCRIPTION OF DRAWINGS
[0054] FIG. 1a is angular power spectra of different frequency
bands in a LOS scenario;
[0055] FIG. 1b is angular power spectra of different frequency
bands in an NLOS scenario;
[0056] FIG. 1c is a simulation result of estimating a channel
characteristic of a high frequency channel by using a low frequency
channel;
[0057] FIG. 2 is a schematic diagram of a communications system
according to an embodiment of this application;
[0058] FIG. 3 is a schematic composition diagram of a
communications apparatus according to an embodiment of this
application;
[0059] FIG. 4 is a flowchart of a beam selection method according
to an embodiment of this application;
[0060] FIG. 5a is an angular power spectrum in a LOS and strong
reflection scenario;
[0061] FIG. 5b is an angular power spectrum in a complex
reflection, scattering, and occlusion scenario;
[0062] FIG. 6 is a schematic diagram of an angle power spectrum
change when a terminal rotates according to an embodiment of this
application;
[0063] FIG. 7 is a flowchart of another beam selection method
according to an embodiment of this application;
[0064] FIG. 8 is a flowchart of still another beam selection method
according to an embodiment of this application;
[0065] FIG. 9 is a schematic composition diagram of a
communications apparatus 90 according to an embodiment of this
application; and
[0066] FIG. 10 is a schematic composition diagram of a beam
selection system according to an embodiment of this
application.
DESCRIPTION OF EMBODIMENTS
[0067] A principle of the embodiments of this application is as
follows: A low frequency channel and a high frequency beam have
similar channel characteristics in a specific angle range (for
example, angles, energy, delays, Doppler, and polarization modes
are basically the same). A relatively small range of a high
frequency beam scanning range is determined by using the channel
characteristic of the low frequency channel, and the determined
high frequency beam scanning range is scanned for the high
frequency beam. In the conventional technology, similar to
processes P1 to P3, a wide beam is first scanned for in a large
range, and then a narrow beam that meets a requirement is finally
determined by performing a plurality of times of scanning based on
the wide beam, while in the embodiments of this application, a
relatively small high frequency beam scanning range is directly
determined based on a channel characteristic of the low frequency
channel, and the high frequency beam is scanned for in a relatively
small angle range. In this way, a scanning time and signaling
overheads of the high frequency beam can be reduced.
[0068] For example, in the conventional technology, when the
terminal uses the wide beam, the terminal may scan for a high
frequency beam of an access network device by performing
level-by-level beam width adjustment. For example, the terminal
first attempts to scan for, in a 60-degree direction, the high
frequency beam sent by the access network device. If the terminal
cannot find the high frequency beam, the terminal attempts to scan
for, in a 50-degree direction, the high frequency beam sent by the
access network device. If the terminal still cannot find the high
frequency beam, the terminal continues to attempt to scan for, in a
40-degree direction, the high frequency beam sent by the access
network device until the high frequency beam is found. This process
requires a longer time of beam selection and pairing. However, when
performing beam scanning according to the foregoing principle, the
terminal may first determine a specific range of a high frequency
beam scanning range based on the channel characteristic of the low
frequency channel, and scan the determined high frequency beam
scanning range for the high frequency beam, without making a
plurality of blind attempts, and taking a longer time.
[0069] Definitions of the high frequency beam and the low frequency
channel in the embodiments of this application are as follows:
[0070] The high frequency beam may be a reference signal in a high
frequency range and in a specific direction. The high frequency
range may be a frequency range above 6 gigahertzes (GHz), for
example, may be a frequency range 2 (frequency range 2, FR2)
specified in the 3rd generation partnership project 3GPP protocol
release (release) 15.
[0071] The low frequency channel may be a transmission channel in a
low frequency range, for example, may be a carrier in the low
frequency range, or may be a BWP and another frequency domain
resource in the low frequency range. The low frequency range may be
a frequency range below or equal to 6 GHz, for example, may be a
frequency range 1 (frequency range 1, FR1) specified in the 3GPP
release 15. It should be noted that the high frequency beam and the
low frequency channel are relative concepts, and a frequency band
of the high frequency beam may be greater than the low frequency
channel. In the embodiments of this application, a carrier in a
frequency range greater than 6 GHz is referred to as a high
frequency beam, and a carrier in a frequency range less than or
equal to 6 GHz is referred to as a low frequency channel.
Alternatively, a carrier greater than a preset frequency band may
be referred to as a high frequency beam, and a carrier less than or
equal to the preset frequency band may be referred to as a low
frequency channel. The preset frequency band may be set based on a
requirement. This is not limited herein.
[0072] For example, FIG. 1a is angular power spectra of different
frequency bands in a line of sight (line of sight, LOS) scenario,
where a horizontal axis represents a direction of a channel or a
beam transmitted between a terminal and an access network device,
and a vertical axis represents normalized signal strength, that is,
signal strength of each multipath is divided by strongest power. As
shown in FIG. 1a, when a low frequency is 5.8 GHz, energy is
concentrated in a 15-degree direction, and when a high frequency is
14.8 GHz and a high frequency is 58.7 GHz, capability is also
concentrated in a direction about 15 degrees. It can be learned
from FIG. 1a that, in the LOS scenario, a capability concentration
angle of a low frequency channel is roughly the same as that of a
high frequency beam, and a direction of a high frequency beam is
basically the same as that of a low frequency channel.
[0073] FIG. 1b is angular power spectra of different frequency
bands in a non-line of sight (non-line of sight, NLOS) scenario. A
horizontal axis represents a direction of a channel or a beam
transmitted between a terminal and an access network device, and a
vertical axis represents normalized signal quality. As shown in
FIG. 1b, when a low frequency is 5.8 GHz, energy of a low frequency
channel in a 15-degree direction is the largest, and energy of a
low frequency channel in a direction about -50 degrees is the
second largest. When a high frequency is 14.8 GHz, energy in the
15-degree direction is also the largest, and energy of a high
frequency beam in a direction about -80 degrees is the second
largest. It can be learned from FIG. 1b that, if a high frequency
beam with better signal quality is scanned for, the high frequency
beam may be scanned for in a direction about 15 degrees and in a
direction about -80 degrees.
[0074] It can be learned from FIG. 1a and FIG. 1b that an energy
concentration direction of the low frequency channel is
approximately the same as or differs from a capability
concentration direction of the high frequency beam by a specific
angle range. Therefore, a channel characteristic of the low
frequency channel may be measured. A direction of the low frequency
channel prevails, and the high frequency beam may be scanned for in
a specific range centered in the direction.
[0075] According to research, in different communication scenarios,
a peak to average ratio (peak to average ratio, PAR) of the low
frequency channel is different, and a high frequency beam scanning
range is determined by using the channel characteristic of the low
frequency channel. Accuracy of a high frequency beam obtained by
scanning the determined high frequency beam scanning range may be
different from an actually sent high frequency beam. A larger PAR
indicates higher accuracy between the high frequency beam obtained
by scanning the high frequency beam scanning range determined by
using the channel characteristic of the low frequency channel and
the actually sent high frequency beam. A smaller PAR indicates
lower accuracy between the high frequency beam obtained by scanning
the high frequency beam scanning range determined by using the
channel characteristic of the low frequency channel and the
actually sent high frequency beam.
[0076] For example, FIG. 1c is a simulation result of estimating a
channel characteristic of a high frequency channel by using a low
frequency channel. A horizontal axis represents a ratio of a
strongest multipath to an average value in an angular power
spectrum. A vertical axis represents accuracy of estimating an
angle of the high frequency channel by using the low frequency
channel. As shown in FIG. 1c, when the PAR is greater than or equal
to 4, accuracy between a high frequency beam obtained by scanning a
high frequency beam scanning range determined by using a channel
characteristic of the low frequency channel and an actually sent
high frequency beam may reach 98%, which is relatively high.
However, when the PAR is 2, the accuracy between the high frequency
beam obtained by scanning the high frequency beam scanning range
determined by using the channel characteristic of the low frequency
channel and the actually sent high frequency beam is only about
77%, which is relatively low. In view of this, to improve the
accuracy between the high frequency beam obtained by scanning the
high frequency beam scanning range determined by using the channel
characteristic of the low frequency channel and the actually sent
high frequency beam, different high frequency beam scanning ranges
need to be determined based on different PARs of the low frequency
channel.
[0077] The following describes, according to the foregoing
principle, the beam selection method provided in the embodiments of
this application.
[0078] The beam selection method provided in the embodiments of
this application may be applicable to a communications system
supporting high frequency communication and low frequency
communication. For example, the communications system may be a
cellular communications system, may be a long term evolution (long
term evolution, LTE) system, or may be a fifth generation (5th
generation, 5G) mobile communications system, or may be a new radio
(new radio, NG) system, or may be another mobile communications
system. This is not limited. The following uses only a
communications system shown in FIG. 2 as an example to describe the
method provided in the embodiments of this application.
[0079] FIG. 2 is a schematic architectural diagram of the
communications system according to an embodiment of this
application. As shown in FIG. 2, the communications system includes
an access network device and a plurality of terminals. The terminal
may communicate with the access network device by using a high
frequency beam, or may communicate with the access network device
by using a low frequency channel, or may communicate with the
access network device in a low frequency channel and a high
frequency beam coordination manner. In a scenario in which the
terminal communicates with the access network device by using the
high frequency beam, the terminal and the access network device may
form a plurality of beam pairs between the terminal and the access
network device by using a beamforming technology, and send and
receive data on the beam pairs. In this embodiment of this
application, the terminal may determine, based on a channel
characteristic of the low frequency channel, a high frequency beam
scanning range used to scan for a high frequency beam, and scan the
high frequency beam scanning range for the high frequency beam sent
by the access network device. Specifically, for an implementation
process, refer to the description in an embodiment corresponding to
FIG. 4.
[0080] The terminal in FIG. 2 has a plurality of low frequency
omnidirectional antenna arrays and a plurality of high frequency
antenna arrays, and may perform low frequency communication with
the access network device, or may perform high frequency
communication with the access network device. The terminal in FIG.
2 may be referred to as a terminal device (terminal device), user
equipment (user equipment, UE), a mobile station (mobile station,
MS), a mobile terminal (mobile terminal, MT), or the like, and may
be deployed on water (for example, on a ship); or may be deployed
in the air (for example, on a plane, a balloon, or a satellite).
Specifically, the terminal in FIG. 2 may be a mobile phone (mobile
phone), a tablet computer, or a computer having a wireless
transceiver function. Alternatively, the terminal may be a virtual
reality (virtual reality, VR) terminal, an augmented reality
(augmented reality, AR) terminal, a wireless terminal in industrial
control, a wireless terminal in self-driving, a wireless terminal
in telemedicine, a wireless terminal in a smart grid, a wireless
terminal in a smart city (smart city), a wireless terminal in a
smart home (smart home), or the like. In the embodiments of this
application, an apparatus for implementing a function of the
terminal may be a terminal, or may be an apparatus that can support
the terminal in implementing the function, for example, a chip
system. In technical solutions provided in the embodiments of this
application, an example in which an apparatus for implementing a
terminal function is a terminal is used to describe the technical
solutions provided in the embodiments of this application.
[0081] The access network device in FIG. 2 may be referred to as an
access network, and is mainly configured to implement functions
such as a radio physical control function, resource scheduling and
radio resource management, radio access control, and mobility
management. The access network device may perform low frequency
communication with the terminal, or may perform high frequency
communication with the terminal. Specifically, the access network
device may be an access network (access network, AN) device/a radio
access network (radio access network, RAN) device, may be a device
including a plurality of 5G-AN/5G-RAN nodes, or may be any node of
a nodeB (nodeB, NB), an evolved nodeB (evolution nodeB, eNB), a
next generation nodeB (generation NodeB, gNB), a transmission
reception point (transmission reception point, TRP), a transmission
point (transmission point, TP), or another access node. In this
embodiment of this application, an apparatus configured to
implement a function of the access network device may be an access
network device, or may be an apparatus, for example, a chip system,
that can support the access network device in implementing the
function. This is not limited.
[0082] For example, the access network device is a base station.
The base station in FIG. 2 may be a device in which a low frequency
and a high frequency are co-sited. For example, the base station
may be a device in which an NR high frequency and LTE are co-sited,
or may be a device in which an NR low frequency and an NR high
frequency are co-sited, or a device in which an NR high frequency
and wireless emulation (wireless fidelity, WI-FI) are co-sited, or
the like. Alternatively, the base station in FIG. 2 may
alternatively be non-co-sited. This is not limited.
[0083] It should be noted that FIG. 2 is merely a figure as an
example. A quantity of devices included in FIG. 2 is not limited.
In addition to the devices shown in FIG. 2, the communications
architecture may further include another device, for example, may
further include a core network device or a data network. In
addition, a name of each device in FIG. 2 is not limited. In
addition to names shown in FIG. 2, each device may be named another
name. This is not limited.
[0084] During specific implementation, the terminal shown in FIG. 2
has components shown in FIG. 3. FIG. 3 is a schematic composition
diagram of a communications apparatus 100 according to an
embodiment of this application. The communications apparatus may be
a terminal, a chip in the terminal, or a system-on-a-chip. As shown
in FIG. 3, the communications apparatus 100 includes a processor
110, a sensor module 120, an antenna 1, an antenna 2, a universal
serial bus (universal serial bus, USB) interface 130, a charging
management module 140, a power management module 141, a battery
142, a mobile communications module 150, a wireless communications
module 160, an audio module 170, a speaker 1701, a receiver 1702, a
microphone 1703, a headset jack 1704, an external memory interface
180, an internal memory 181, a button 190, a subscriber identity
module (subscriber identity module, SIM) card interface 191, and
the like. The sensor module 120 may include a gyro sensor 1201, a
magnetometer sensor 1202, an acceleration sensor 1203, a gravity
sensor 1204, and the like.
[0085] The processor 110 in FIG. 3 may include one or more
processing units. For example, the processor 110 may include an
application processor (application processor, AP), a modem
processor, a graphics processing unit (graphics processing unit,
GPU), an image signal processor (image signal processor, ISP), a
controller, a memory, a video codec, a digital signal processor
(digital signal processor, DSP), a baseband processor, and/or a
neural-network processing unit (neural-network processing unit,
NPU). Different processing units may be independent components, or
may be integrated into one or more processors.
[0086] A memory may be further disposed in the processor 110, and
is configured to store instructions and data. In some embodiments,
the memory in the processor 110 is a high-speed cache memory. The
memory may store instructions or data just used or cyclically used
by the processor 110. If the processor 110 needs to use the
instructions or the data again, the processor 110 may directly
invoke the instructions or data from the memory, thereby avoiding
repeated access, reducing a waiting time of the processor 110, and
improving system efficiency.
[0087] In some embodiments, the processor 110 may include one or
more interfaces, for example, may include an inter-integrated
circuit (inter-integrated circuit, I2C) interface, an
inter-integrated circuit sound (inter-integrated circuit sound,
I2S) interface, a pulse code modulation (pulse code modulation,
PCM) interface, a universal asynchronous receiver/transmitter
(universal asynchronous receiver/transmitter, UART) interface, a
mobile industry processor interface (mobile industry processor
interface, MIPI), a general-purpose input/output (general-purpose
input/output, GPIO) interface, a subscriber identity module
(subscriber identity module, SIM) interface, and/or a USB interface
130, or the like.
[0088] The gyro sensor 1201 may be configured to determine a motion
posture of the communications apparatus 100. In some embodiments,
an angular velocity of the communications apparatus 100 around
three axes (namely, axes x, y, and z) may be determined by using
the gyro sensor 1201. The gyro sensor 1201 may be configured to
perform image stabilization during photographing. For example, when
the shutter is pressed, the gyro sensor 1201 detects an angle at
which the communications apparatus 100 shakes, and calculates,
based on the angle, a distance for which a lens module needs to
compensate, so that the lens cancels the shake of the
communications apparatus 100 through reverse motion, to implement
image stabilization. The gyro sensor 1201 may be further used in
navigation and motion sensing game scenarios.
[0089] The magnetometer sensor 1202 includes a Hall sensor. The
communications apparatus 100 may detect opening and closing of a
flip leather case by using the magnetometer sensor 1202. In some
embodiments, when the communications apparatus 100 is a clamshell
phone, the communications apparatus 100 may detect opening and
closing of a flip cover by using the magnetometer sensor 180D.
Further, a feature such as automatic unlocking upon opening of the
flip cover is set based on a detected opening or closing state of
the leather case or a detected opening or closing state of the flip
cover.
[0090] The acceleration sensor 1203 may detect a magnitude of an
acceleration of the communications apparatus 100 in each direction
(usually, three axes). When the communications apparatus 100 is
static, a magnitude and a direction of gravity may be detected. The
acceleration sensor 1203 may be further configured to identify a
posture of the electronic device, and is used in an application
such as switching between landscape mode and portrait mode or a
pedometer.
[0091] The gravity sensor 1204 uses an elastic sensitive element to
make a cantilever-type displacement device, and an energy storage
spring made of the elastic sensitive element to drive an electrical
contact to complete conversion from gravity to an electrical
signal. The gravity sensor measures an acceleration caused by
gravity and calculates a tilt angle of a device relative to a
horizontal plane. For example, a mobile phone with a gravity sensor
can sense a screen status and automatically adjust the screen to
keep level.
[0092] The charging management module 140 is configured to receive
a charging input from a charger. The charger may be a wireless
charger or a wired charger. In some embodiments of wired charging,
the charging management module 140 may receive charging input from
the wired charger through the USB interface 130. In some
embodiments of wireless charging, the charging management module
140 may receive a wireless charging input by using a wireless
charging coil of the communications apparatus 100. The charging
management module 140 may further supply power to the electronic
device by using the power management module 141 while charging the
battery 142.
[0093] The power management module 141 is configured to connect to
the battery 142, the charging management module 140, and the
processor 110. The power management module 141 receives input from
the battery 142 and/or the charging management module 140, and
supplies power to each component of the communications apparatus
100. The power management module 141 may further be configured to
monitor parameters such as a battery capacity, a battery cycle
count, and a battery health status (electric leakage or impedance).
In some other embodiments, the power management module 141 may
alternatively be disposed in the processor 110. In some other
embodiments, the power management module 141 and the charging
management module 140 may alternatively be disposed in a same
device.
[0094] A wireless communication function of the communications
apparatus 100 may be implemented through the antenna 1, the antenna
2, the mobile communications module 150, the wireless
communications module 160, the modem processor, the baseband
processor, and the like.
[0095] The antenna 1 and the antenna 2 are configured to transmit
and receive electromagnetic wave signals. Each antenna in the
communications apparatus 100 may be configured to cover one or more
communication bands. Different antennas may further be multiplexed,
to improve antenna utilization. For example, the antenna 1 may be
multiplexed as a diversity antenna of a wireless local area
network. In some other embodiments, the antenna may be used in
combination with a tuning switch.
[0096] The mobile communications module 150 may provide a wireless
communication solution that includes 2G/3G/4G/5G or the like and
that is applied to the communications apparatus 100. The mobile
communications module 150 may include at least one filter, a
switch, a power amplifier, a low noise amplifier (low noise
amplifier, LNA), and the like. The mobile communications module 150
may receive an electromagnetic wave through the antenna 1, perform
processing such as filtering or amplification on the received
electromagnetic wave, and transfer the electromagnetic wave to the
modem processor for demodulation. The mobile communications module
150 may further amplify a signal modulated by the modem processor,
and convert the signal into an electromagnetic wave for radiation
by using the antenna 1. In some embodiments, at least some
functional modules of the mobile communications module 150 may be
disposed in the processor 110. In some embodiments, at least some
functional modules in the mobile communications module 150 may be
disposed in a same device as at least some modules in the processor
110.
[0097] The modem processor may include a modulator and a
demodulator. The modulator is configured to modulate a low
frequency baseband signal to be sent into a medium and high
frequency signal. The demodulator is configured to demodulate a
received electromagnetic wave signal into a low frequency baseband
signal. Then, the demodulator transmits the low frequency baseband
signal obtained through demodulation to the baseband processor for
processing. The low frequency baseband signal is processed by the
baseband processor, and then transmitted to the application
processor. The application processor outputs a sound signal by
using an audio device (not limited to the speaker 1701, the
receiver 1702, and the like). In some embodiments, the modem
processor may be an independent component. In some other
embodiments, the modem processor may be independent of the
processor 110, and disposed in a same device with the mobile
communications module 150 or another functional module.
[0098] The wireless communications module 160 may provide a
solution for wireless communication such as a wireless local area
network (wireless local area networks, WLAN) (for example, a
wireless fidelity (wireless fidelity, Wi-Fi) network), Bluetooth
(Bluetooth, BT), a global navigation satellite system (global
navigation satellite system, GNSS), frequency modulation (frequency
modulation, FM), a near field communication (near field
communication, NFC) technology, or an infrared (infrared, IR)
technology applied to the communications apparatus 100. The
wireless communications module 160 may be one or more devices that
integrate at least one communication processing module. The
wireless communications module 160 receives an electromagnetic wave
through the antenna 2, performs frequency modulation and filtering
on an electromagnetic wave signal, and sends a processed signal to
the processor 110. The wireless communications module 160 may
further receive a to-be-sent signal from the processor 110, perform
frequency modulation and amplification on the signal, and convert a
processed signal into an electromagnetic wave for radiation through
the antenna 2.
[0099] In some embodiments, the antenna 1 of the communications
apparatus 100 is coupled to the mobile communications module 150,
and the antenna 2 is coupled to the wireless communications module
160, so that the communications apparatus 100 may communicate with
a network and another device by using a wireless communications
technology. The wireless communications technology may include a
global system for mobile communications (global system for mobile
communications, GSM), a general packet radio service (general
packet radio service, GPRS), code division multiple access (code
division multiple access, CDMA), wideband code division multiple
access (wideband code division multiple access, WCDMA),
time-division code division multiple access (time-division code
division multiple access, TD-CDMA), long term evolution (long term
evolution, LTE), BT, a GNSS, a WLAN, NFC, FM, an IR technology,
and/or the like. The GNSS may include a global positioning system
(global positioning system, GPS), a global navigation satellite
system (global navigation satellite system, GLONASS), a BeiDou
navigation satellite system (BeiDou navigation satellite system,
BDS), a quasi-zenith satellite system (quasi-zenith satellite
system, QZSS), and/or a satellite based augmentation system
(satellite based augmentation systems, SBAS).
[0100] The external memory interface 180 may be configured to
connect to an external storage card, for example, a micro SD card,
to extend a storage capability of the communications apparatus 100.
The external storage card communicates with the processor 110
through the external memory interface 180, to implement a data
storage function. For example, files such as music and a video are
stored in the external storage card.
[0101] The internal memory 181 may be configured to store
computer-executable program code. The executable program code
includes instructions. The processor 110 runs the instructions
stored in the internal memory 181 to perform various function
applications of the communications apparatus 100 and process data.
The internal memory 181 may include a program storage area and a
data storage area. The program storage area may store an operating
system, an application required by at least one function (such as a
sound playing function or an image playing function), and the like.
The data storage area may store data (such as audio data and an
address book) created during use of the communications apparatus
100, and the like. In addition, the internal memory 181 may include
a high-speed random access memory, and may further include a
nonvolatile memory, for example, at least one magnetic disk storage
device, a flash memory device, or a universal flash storage
(universal flash storage, UFS).
[0102] The communications apparatus 100 may implement an audio
function, for example, music playing and recording, by using the
audio module 170, the speaker 1701, the receiver 1702, the
microphone 1703, the headset jack 1704, the application processor,
and the like.
[0103] The audio module 170 is configured to convert digital audio
information into an analog audio signal output, and is also
configured to convert an analog audio input into a digital audio
signal. The audio module 170 may be further configured to: code and
decode an audio signal. In some embodiments, the audio module 170
may be disposed in the processor 110, or some functional modules of
the audio module 170 are disposed in the processor 110.
[0104] The speaker 1701, also referred to as a "horn", is
configured to convert an audio electrical signal into a sound
signal. The communications apparatus 100 may be configured to
listen to music or answer a hands-free call by using the speaker
170A.
[0105] The receiver 1702, also referred to as an "earpiece", is
configured to convert an audio electrical signal into a sound
signal. When the communications apparatus 100 is configured to
answer a call or listen to voice information, the receiver 170B may
be placed close to a human ear to listen to a voice.
[0106] The microphone 1703, also referred to as a "mike" or a
"microphone", is configured to convert a sound signal into an
electrical signal. When making a call, sending voice information,
or needing to trigger, by using a voice assistant, the
communications apparatus 100 to perform some functions, a user may
make a sound near the microphone 1703 by using a human mouth, and
input a sound signal to the microphone 1703. At least one
microphone 1703 may be disposed in the communications apparatus
100. In some other embodiments, two microphones 1703 may be
disposed in the communications apparatus 100, to implement a noise
reduction function, in addition to collecting a sound signal. In
some other embodiments, three, four, or more microphones 1703 may
be alternatively disposed in the communications apparatus 100, to
collect a sound signal and reduce noise. The microphones may
further identify a sound source, implement a directional recording
function, and the like.
[0107] The headset jack 1704 is configured to connect to a wired
headset. The headset jack 1704 may be the USB interface 130, or may
be a 3.5 mm open mobile terminal platform (open mobile terminal
platform, OMTP) standard interface, or a cellular
telecommunications industry association of the USA (cellular
telecommunications industry association of the USA, CTIA) standard
interface.
[0108] The button 190 includes a power button, a volume button, and
the like. The button 190 may be a mechanical button, or may be a
touch button. The communications apparatus 100 may receive button
input, and generate button signal input related to user setting and
function control of the communications apparatus 100.
[0109] The SIM card interface 191 is configured to connect to a SIM
card. The SIM card may be inserted into the SIM card interface 191
or removed from the SIM card interface 191, to implement contact
and separation from the communications apparatus 100. The
communications apparatus 100 may support one or N SIM card
interfaces, and N is a positive integer greater than 1. The SIM
card interface 191 may support a nano SIM card, a micro SIM card, a
SIM card, and the like. A plurality of cards may be simultaneously
inserted into a same SIM card interface 191. The plurality of cards
may be of a same type or of different types. The SIM card interface
191 may also be compatible with different types of SIM cards. The
SIM card interface 191 may also be compatible with an external
storage card. The communications apparatus 100 interacts with a
network by using the SIM card, to implement functions such as
calling and data communication. In some embodiments, the
communications apparatus 100 uses an eSIM, namely, an embedded SIM
card. The eSIM card may be embedded in the communications apparatus
100, and cannot be separated from the communications apparatus
100.
[0110] It may be understood that the software system of the
communications apparatus 100 may use a layered architecture, an
event-driven architecture, a microkernel architecture, a micro
service architecture, or a cloud architecture. In this embodiment,
an Android system with a layered architecture is used as an example
to describe a software structure of the communications apparatus
100. In addition, the structure shown in this embodiment does not
constitute a specific limitation on the communications apparatus
100. In some other embodiments, the communications apparatus 100
may include more or fewer components than those shown in the
figure, or some components may be combined, or some components may
be split, or there may be a different component layout. The
components shown in FIG. 3 may be implemented by using hardware,
software, or a combination of software and hardware.
[0111] The following describes, according to the foregoing
principle and with reference to the system shown in FIG. 2, a beam
selection method provided in the embodiments of this application.
Each device in the following method embodiment may have components
shown in FIG. 3. Details are not described again. In addition, in
the following embodiments of this application, names of messages
between network elements, names of parameters in messages, or the
like are merely examples, and there may be other names during
specific implementation. This is not specifically limited in the
embodiments of this application.
[0112] FIG. 4 is a beam selection method according to an embodiment
of this application. As shown in FIG. 4, the method may include the
following steps.
[0113] Step 401: A terminal determines a first angular power
spectrum of a low frequency channel transmitted between the
terminal and an access network device.
[0114] The access network device may be the access network device
in FIG. 2, and the terminal may be any terminal in FIG. 2. The
access network device and the terminal may transmit the low
frequency channel, or may transmit a high frequency beam.
[0115] The low frequency channel transmitted between the terminal
and the access network device may be a low frequency channel (or
referred to as a downlink low frequency channel) sent by the access
network device to the terminal. At a same moment, the access
network device may send a plurality of low frequency channels to
the terminal at a same moment. Alternatively, when there is
reciprocity between a channel sent by the terminal to the access
network device and a channel sent by the access network device to
the terminal, a transmission channel between the terminal and the
access network device may alternatively be a low frequency channel
(or referred to as an uplink low frequency channel) sent by the
terminal to the access network device. In this way, a high
frequency beam (or referred to as a downlink high frequency beam)
sent by the access network device to the terminal may be determined
by using a channel characteristic of the uplink low frequency
channel. At a same moment, the terminal may send a plurality of low
frequency channels to the access network device.
[0116] The first angular power spectrum may reflect a curve
relationship between an angle of the low frequency channel and
power of the low frequency channel, and the first angular power
spectrum may include a direction of arrival (direction of arrival,
DOA) power spectrum or a direction of departure (direction of
departure, DOD) power spectrum.
[0117] For example, when the low frequency channel transmitted
between the terminal and the access network device is the low
frequency channel sent by the access network device to the
terminal, the terminal may determine a DOA power spectrum of the
low frequency channel. When the low frequency channel transmitted
between the terminal and the access network device is the low
frequency channel sent by the terminal to the access network
device, the terminal may determine a DOD power spectrum of the low
frequency channel.
[0118] The DOA power spectrum may reflect a curve relationship
between an angle at which the low frequency channel arrives at the
terminal and the power of the low frequency channel, and the DOD
power spectrum may reflect a curve relationship between an angle at
which the low frequency channel leaves the terminal and the power
of the low frequency channel. The terminal may determine the DOA
angular power spectrum or the DOD power spectrum by using the
conventional technology. Details are not described. For a same low
frequency channel, a DOA power spectrum determined by the terminal
is the same as a DOD power spectrum determined by the terminal, and
the DOA power spectrum and the DOD power spectrum may be
collectively referred to as an angular power spectrum.
[0119] Step 402: The terminal determines a first high frequency
beam scanning range based on the first angular power spectrum.
[0120] The first high frequency beam scanning range may be an angle
range centered on the angle of a low frequency channel, and the
terminal may scan for, in the angle range, the high frequency beam
sent by the access network device. In this embodiment of this
application, an angle of one low frequency channel may correspond
to one high frequency beam scanning beam, and angles of a plurality
of low frequency channels may correspond to a plurality of high
frequency beam scanning ranges.
[0121] For example, the terminal may calculate a peak-to-average
ratio of the low frequency channel based on the first angular power
spectrum, and determine the first high frequency beam scanning
range based on the peak-to-average ratio of the low frequency
channel.
[0122] That the terminal calculates a peak-to-average ratio of the
low frequency channel based on the first angular power spectrum may
include: The terminal obtains a maximum peak value and an average
value from the first angular power spectrum, and calculates a ratio
of the maximum peak value to the average value to obtain the
peak-to-average ratio of the low frequency channel. For example,
when the first angular power spectrum is the DOA power spectrum,
the terminal may obtain the maximum peak value and the average
value from the DOA power spectrum, and calculate the ratio of the
maximum peak value to the average value to obtain the
peak-to-average ratio of the low frequency channel. When the first
angular power spectrum is the DOD power spectrum, the terminal may
obtain the maximum peak value and the average value from the DOD
power spectrum, and calculate the ratio of the maximum peak value
to the average value to obtain the peak-to-average ratio of the low
frequency channel.
[0123] For example, FIG. 5a is an angular power spectrum of the low
frequency channel in a LOS and strong reflection scenario. It can
be learned from FIG. 5a that the average value is about 0.22, and
the maximum peak value is 1. In this case, the peak-to-average
ratio may be 1/0.2245. FIG. 5b is an angular power spectrum of a
low frequency channel in a complex transmission, scattering, and
occlusion scenario. It can be learned from FIG. 5b that the average
value is about 0.5, and the maximum peak value is 1. In this case,
the peak-to-average ratio may be 1/0.5=2.
[0124] That the terminal determines a first high frequency beam
scanning range based on the first angular power spectrum may
include: The terminal determines, based on a correspondence between
the peak-to-average ratio of the low frequency channel and a high
frequency beam region range, a first region range corresponding to
the peak-to-average ratio of the low frequency channel, and
determines, based on the first high frequency beam region range and
an angle of a low frequency channel whose peak value is a first
threshold, the first high frequency beam scanning range, where a
range size of the first high frequency beam scanning range is the
same as a range size of the first region range, and a center angle
of the first high frequency beam scanning range may be the angle of
the low frequency channel whose peak value is the first
threshold.
[0125] The first threshold may be set as required. Optionally, the
low frequency channel whose peak value is the first threshold may
be a low frequency channel with a maximum peak value in all low
frequency channels, or may be one or more low frequency channels
whose peak values are greater than or equal to a threshold. The
threshold may be set as required.
[0126] It should be noted that, in the embodiments of this
application, the angle of the low frequency channel may be a main
path direction of the low frequency channel, and the main path
direction of the low frequency channel may be a direction with
maximum energy on the low frequency channel. For example, as shown
in FIG. 5a, a main path direction of a low frequency channel 1 is
approximately 70 degrees.
[0127] In this embodiment of this application, the correspondence
between the peak-to-average ratio and the high frequency beam
region range may be preset. A larger peak-to-average ratio
indicates a better current communication environment, an energy
concentration range of the low frequency channel is relatively
close to the high frequency beam, and the high frequency beam
region range corresponding to the peak-to-average ratio is smaller.
In this case, the high frequency beam may be scanned for in an
angle range close to the low frequency channel. A smaller
peak-to-average ratio indicates a poorer current communication
environment, an energy concentration range of the low frequency
channel is relatively far away from the high frequency beam, and
the high frequency beam region range corresponding to the
peak-to-average ratio is approximately larger. In this case, the
high frequency beam may be scanned for in an angle range far from
the low frequency channel. For example, the following is the
correspondence between the peak-to-average ratio and the high
frequency beam region range:
[0128] when the peak-to-average ratio is greater than or equal to
4, the high frequency beam region range is from -5 degrees to +5
degrees;
[0129] when the peak-to-average ratio is less than 4 and is greater
than or equal to 3, the high frequency beam region range is from
-10 degrees to +10 degrees;
[0130] when the peak-to-average ratio is less than 3 and is greater
than or equal to 2, the high frequency beam region range is from
-20 degrees to +20 degrees;
[0131] when the peak-to-average ratio is less than 2 and is greater
than or equal to 1, the high frequency beam region range is from
-30 degrees to +30 degrees; and
[0132] when the peak-to-average ratio is less than 1, the first
high frequency beam scanning range may not need to be determined,
and the high frequency beam sent by the access network device is
scanned for in phases P1 to P3 by using the conventional
technology.
[0133] For example, an angle of a low frequency channel with a
maximum peak value in the first high frequency beam scanning range
is used as a center. For example, as shown in FIG. 5a, the PAR is
about 4.5, the PAR is greater than 4, and a corresponding scanning
range is from -5 degrees to +5 degrees. It can be learned from FIG.
5a that the angle of the low frequency channel with the maximum
peak is about 70 degrees. In this case, the terminal may determine
that the first high frequency beam scanning range is from 65
degrees to 75 degrees centered on 70 degrees.
[0134] For another example, as shown in FIG. 5b, the PAR is about
2, the PAR is greater than 2 and less than 3, and a corresponding
scanning range is a range from -20 degrees to +20 degrees. It can
be learned from FIG. 5b that the angle of the low frequency channel
with the maximum peak value is about 70 degrees. In this case, the
terminal may determine that the first high frequency beam scanning
range is from 50 degrees to 90 degrees centered on 70 degrees.
[0135] Step 403: The terminal scans the first high frequency beam
scanning range for the high frequency beam sent by the access
network device.
[0136] The access network device may send the high frequency beam
to the terminal by using the conventional technology. For example,
the access network device may send the high frequency beam to the
terminal in a large range (in a plurality of directions).
Alternatively, the access network device may send the high
frequency beam to the terminal by using the following method.
[0137] The access network device determines an angular power
spectrum of a low frequency channel transmitted between the access
network device and the terminal, calculates, based on the angular
power spectrum of the low frequency channel, a peak-to-average
ratio of the low frequency channel transmitted between the terminal
and the access network device, determines a high frequency beam
sending range based on the peak-to-average ratio of the low
frequency channel, and sends the high frequency beam to the
terminal in the high frequency beam sending range. In this way, the
high frequency beam may be sent to the terminal in a specific angle
range, and the high frequency beam does not need to be sent in a
large range as in the conventional technology, thereby reducing
reference signal resources and network resources occupied for
sending the high frequency beam.
[0138] When the low frequency channel transmitted between the
terminal and the access network device is the low frequency channel
sent by the access network device to the terminal, the access
network device may determine the DOD power spectrum of the low
frequency channel, obtain the maximum peak value and the average
value from the DOD power spectrum, and calculate the ratio of the
maximum peak value to the average value, to obtain the
peak-to-average ratio. When the low frequency channel transmitted
between the terminal and the access network device is the low
frequency channel sent by the terminal to the access network
device, the access network device may determine the direction of
arrival DOA power spectrum of the low frequency channel, obtain the
maximum peak value and the average value from the DOA power
spectrum, and calculate the ratio of the maximum peak value to the
average value, to obtain the peak-to-average ratio.
[0139] That the access network device determines a high frequency
beam sending range based on the calculated peak-to-average ratio
may include: A larger peak-to-average ratio indicates a better
current communication environment, an energy concentration range of
the low frequency channel is close to that of the high frequency
beam, and the determined high frequency beam sending range is
closer to the angle of the low frequency channel. For example, when
the peak-to-average ratio is greater than or equal to 4, it is
determined that the high frequency beam sending range is .+-.5
degrees of the angle of the low frequency channel whose peak value
is the first threshold. When the peak-to-average ratio is less than
4 and is greater than or equal to 3, it is determined that the high
frequency beam sending range is .+-.10 degrees of the angle of the
low frequency channel whose peak value is the first threshold. When
the peak-to-average ratio is less than 3 and is greater than or
equal to 2, it is determined that the high frequency beam sending
range is .+-.20 degrees of the angle of the low frequency channel
whose peak value is the first threshold. When the peak-to-average
ratio is less than 2 and is greater than or equal to 1, it is
determined that the high frequency beam sending range is .+-.30
degrees of the angle of the low frequency channel whose peak value
is the first threshold. When the peak-to-average ratio is less than
1, the high frequency beam sending range may not need to be
determined, but the high frequency beam is sent to the terminal in
a relatively large range by using the conventional technology.
[0140] That the terminal scans for the high frequency beam sent by
the access network device may be: The terminal measures signal
quality of the high frequency beam, for example, measures reference
signal received power (reference signal received power, RSRP),
reference signal received quality (reference signal received
quality, RSRQ), a reference signal received strength indicator
(received signal strength indicator, RSSI), a block error rate
(block error rate, BLER), a signal to interference and noise ratio
(signal to interference and noise ratio, SINR), a channel quality
indicator (channel quality indicator, CQI) of the high frequency
beam.
[0141] Based on the method shown in FIG. 4, when scanning for the
high frequency beam delivered by the access network device, the
terminal may determine the first high frequency beam scanning range
based on the angular power spectrum of the low frequency channel,
and scan the first high frequency beam scanning range for the high
frequency beam sent by the access network device. In this way, the
terminal may scan a specific range for the high frequency beam, and
does not need to scan a large range for the high frequency beam by
using three phases P1 to P3 as in the conventional technology.
Compared with the conventional technology, the method provided in
FIG. 4 reduces a scanning time. In addition, signaling interaction
with the access network device does not need to be performed for a
plurality of times, thereby reducing signaling overheads.
[0142] In a first embodiment of the method shown in FIG. 4,
further, after the terminal completes scanning of the high
frequency beam in the first high frequency beam scanning range, the
terminal may indicate, to the access network device, information
about a scanned high frequency beam with better signal quality, so
that the access network device sends data to the terminal on a high
frequency beam with optimal signal quality. The information about
the high frequency beam may include any one or more types of the
following information: an index number of the high frequency beam,
an angle of the high frequency beam, information about a reference
signal corresponding to the high frequency beam, information about
a low frequency channel adjacent to the high frequency beam, and
the like. This is not limited.
[0143] For example, as shown in FIG. 5a, the PAR is 4.5, and the
PAR is greater than 4. It can be learned from FIG. 5a that a low
frequency channel with a maximum peak value is located at about 70
degrees, and a low frequency channel with a second largest peak
value is located at about 23 degrees. In this case, the terminal
may scan for, in a range of 65 degrees to 75 degrees and in a range
of 18 degrees to 28 degrees, the high frequency beam sent by the
access network device. If signal quality of a high frequency beam
found by the terminal in the range of 65 degrees to 75 degrees is
10 db, and signal quality of a high frequency beam found in the
range of 18 degrees to 28 degrees is 3 db, the terminal may report
related information about the high frequency beam in the range of
65 degrees to 75 degrees to the access network device, so that the
access network device sends data in the range of 65 degrees to 75
degrees by using the high frequency beam.
[0144] It should be noted that, to prevent normal data transmission
from being affected when the terminal fails to select a high
frequency beam with better signal quality from the determined high
frequency beam range, or when the terminal fails to receive data on
a found high frequency beam, in the process shown in FIG. 4, the
terminal may select one or more candidate beams based on the first
angular power spectrum, so as to receive data on the selected
candidate beam. Specifically, a process in which the terminal
selects the candidate beam based on the first angular power
spectrum is as follows:
[0145] When the peak-to-average ratio is greater than or equal to
4, the terminal selects one candidate beam, and an angle of the
candidate beam is an angle of a low frequency channel whose energy
is a second largest peak value. For example, as shown in FIG. 5a,
if the terminal scans for no high frequency beam with optimal
signal quality in the range of 65 degrees to 75 degrees, the
terminal may use the high frequency beam in the range of 18 degrees
to 28 degrees as the candidate beam.
[0146] When the peak-to-average ratio is less than 4 and is greater
than or equal to 3, the terminal selects two candidate beams, where
the two candidate beams correspond to two low frequency channels
whose energy is a second largest peak value, and angles of the
candidate beams are angles of the low frequency channels whose
energy is the second largest peak value.
[0147] When the peak-to-average ratio is less than 3 and is greater
than or equal to 2, the terminal selects three candidate beams,
where the three candidate beams correspond to three low frequency
channels whose energy is the second largest peak value, and angles
of the candidate beams are angles of the low frequency channels
that correspond to the three candidate beams and whose energy is
the second largest peak value. When the peak-to-average ratio is
less than 2 and is greater than or equal to 1, the terminal selects
four candidate beams, where the four candidate beams correspond to
four low frequency channels whose energy is greater than the second
largest peak value, and angles of the candidate beams are angles of
the low frequency channels that correspond to the candidate beams
and whose energy is the second largest peak value.
[0148] In this way, when high frequency beam scanning fails or high
frequency beam communication fails, high frequency communication
may be performed by using the candidate beam, to ensure normal data
transmission.
[0149] In a second embodiment of the method shown in FIG. 4, when
the terminal performs step 401, the terminal may further determine
whether the access network device is included in a whitelist. If
the access network device is included in the whitelist, the
terminal may perform step 401 to determine the first angular power
spectrum, determine the first high frequency beam scanning range
based on the first angular power spectrum, and scan the first high
frequency beam scanning range for the high frequency beam. On the
contrary, if the whitelist does not include information about the
access network device, and the information about the access network
device is included in a blacklist, the terminal does not scan for,
in the manner shown in FIG. 4, the high frequency beam sent by the
access network device.
[0150] The information about the access network device may be used
to indicate the access network device, for example, may be an
internet protocol (internet protocol, IP) address of the access
network device, or may be media access control (media access
control, MAC) of the access network device, or may be other
information used to identify the access network device. This is not
limited.
[0151] The whitelist may include information about one or more
access network devices, and the access network device included in
the whitelist may perform high frequency communication with the
terminal, or may perform low frequency communication with the
terminal. In addition, a channel characteristic when the access
network device performs high frequency communication with the
terminal is basically the same as a channel characteristic when the
access network device performs low frequency communication with the
terminal.
[0152] For example, when the terminal accesses an access network
device for the first time, the terminal may scan for, in existing
phases P1 to P3, a high frequency beam delivered by the access
network device, and scan for the high frequency beam in the manner
shown in FIG. 4. If the high frequency beam determined by scanning
in the phases P1 to P3 is the same as the high frequency beam find
by the terminal in the manner shown in FIG. 4, the terminal
determines to add information about the access network device to
the whitelist. Subsequently, if the terminal needs to manage the
high frequency beam of the access network device, the terminal may
view the whitelist. When the terminal finds that the whitelist
includes the information about the access network device, the
terminal directly manages the high frequency beam of the access
network device management in the manner shown in FIG. 4, and does
not need to scan for, in the phases P1 to P3, the high frequency
beam delivered by the access network device.
[0153] On the contrary, if the high frequency beam determined by
scanning in the phases P1 to P3 is different from the high
frequency beam found by the terminal in the manner shown in FIG. 4,
or the access network device fails to send the high frequency beam
to the terminal for a plurality of times in the angle range of the
low frequency channel, it indicates that the high frequency beam
cannot be found by using the channel characteristic of the low
frequency channel in a range centered on the angle of the low
frequency channel, and the access network device is added to the
blacklist. Subsequently, if the terminal needs to manage the high
frequency beam of the access network device in the blacklist, the
terminal may scan for, in the existing phases P1 to P3, the high
frequency beam delivered by the access network device.
[0154] The blacklist may include information about one or more
access network devices that do not support beam scanning by using
the channel characteristic of the low frequency channel. When the
terminal determines that the information about the access network
device is not included in the blacklist, the terminal performs step
401 to determine the first angular power spectrum, determine the
first high frequency beam scanning range based on the first angular
power spectrum, and scan the first high frequency beam scanning
range for the high frequency beam. On the contrary, if the terminal
determines that the information about the access network device is
included in the blacklist, the terminal does not scan for, in the
manner shown in FIG. 4, the high frequency beam sent by the access
network device, but scans for, in the existing phases P1 to P3, the
high frequency beam delivered by the access network device.
[0155] For example, the whitelist includes {an access network
device 1 and an access network device 2}, and the blacklist
includes {an access network device 4 and an access network device
5}. Before scanning for the high frequency beam sent by the access
network device 1, the terminal may view the whitelist. If the
terminal finds that the set includes information about the access
network device 1, the terminal may determine the first high
frequency beam scanning range in the manner shown in step 402 and
step 403, and scan the first high frequency beam scanning range for
a high frequency beam sent by the access network device 1. Before
scanning for a high frequency beam sent by an access network device
3, the terminal views the whitelist, and finds that the set does
not include information about the access network device 3. In
addition, the terminal views the blacklist, and finds that the
blacklist includes information about the access network device 4.
In this case, the terminal does not scan for the high frequency
beam in the manner shown in step 402 and step 403, but scans for,
in the existing phases P1 to P3, a high frequency beam delivered by
the access network device 3.
[0156] In a third embodiment of the method shown in FIG. 4, in a
time period after the terminal performs step 401 and before step
402, the terminal is likely to rotate. Consequently, the first
angular power spectrum between the terminal and the access network
device changes. To avoid a problem that the angular power spectrum
of the low frequency channel changes after the terminal rotates,
and the first high frequency beam scanning range determined based
on the angular power spectrum of the low frequency channel has a
relatively large error, the method may further include:
[0157] The terminal determines whether the terminal rotates, and if
the terminal rotates, the terminal corrects the first angular power
spectrum based on a rotation angle of the terminal. Further
optionally, the terminal calculates the PAR of the low frequency
channel based on the corrected first angular power spectrum,
determines the first high frequency beam scanning range based on
the PAR of the low frequency channel, and scans for, in the first
high frequency beam scanning range, the high frequency beam sent by
the access network device.
[0158] The terminal may detect, by using a sensor (a gyro sensor, a
magnetometer sensor, an acceleration sensor, and the like)
installed on the terminal, whether the terminal rotates.
Specifically, for a detection process, refer to the conventional
technology. Details are not described again.
[0159] That the terminal corrects the first angular power spectrum
based on a rotation angle of the terminal may include: The terminal
rotates the first angular power spectrum based on the rotation
angle of the terminal, so that a rotation angle of the first
angular power spectrum is the same as the rotation angle of the
terminal.
[0160] For example, as shown in FIG. 6, when the terminal rotates
by 30 degrees, the angular power spectrum also rotates by 30
degrees. For example, the angle of the low frequency channel
corresponding to a maximum peak value rotates from about 70 degrees
to about 40 degrees, and the angle of the low frequency channel
corresponding to the second largest peak value rotates from about
25 degrees to about 15 degrees. The PAR is still kept at about 4.5.
In this case, the terminal may scan for the high frequency beam in
a range of 35 degrees to 45 degrees, and scan for the high
frequency beam at about 10 degrees to 20 degrees.
[0161] In this way, when the terminal rotates, the first angular
power spectrum can be corrected in time, to ensure accuracy of the
first angular power spectrum, and further improve accuracy of the
first high frequency beam scanning range determined based on the
first angular power spectrum.
[0162] In a fourth embodiment of the method shown in FIG. 4, after
step 401, the terminal is likely to move. Consequently, the channel
characteristic of the low frequency channel between the terminal
and the access network device changes. To avoid a problem that the
angular power spectrum of the low frequency channel changes due to
the change of the channel characteristic between the terminal and
the access network device after the terminal moves, and the first
high frequency beam scanning range determined based on the angular
power spectrum has a relatively large error, the method may further
include:
[0163] The terminal determines whether the terminal moves. If the
terminal moves and a moving distance of the terminal is greater
than a channel correlation distance, it indicates that the channel
characteristic of the low frequency channel between the terminal
and the access network device changes, and the terminal needs to
re-determine the angular power spectrum of the low frequency
channel transmitted between the terminal and the access network
device. For example, the terminal determines a second angular power
spectrum of the low frequency channel transmitted between the
terminal and the access network device. Further optionally, the
terminal determines a second high frequency beam scanning range
based on the re-determined angular power spectrum (for example, the
second angular power spectrum), and scans the second high frequency
beam scanning range for the high frequency beam sent by the access
network device.
[0164] If the terminal does not move, or the terminal moves, but
the moving distance is less than or equal to the channel
correlation distance, the terminal may determine the first high
frequency beam scanning range based on the angular power spectrum
determined in step 401, and scan the first high frequency beam
scanning range for the high frequency beam sent by the access
network device.
[0165] The terminal may detect, by using a sensor (a gyro sensor, a
magnetometer sensor, an acceleration sensor, a gravity sensor, and
the like) installed on the terminal, whether the terminal moves.
For example, if a value collected by any sensor changes and a
change value is greater than or equal to a threshold, it is
determined that the terminal moves, or if values collected by all
sensors do not change, or if values collected by the sensors
change, but the change values are less than or equal to a
threshold, it is determined that the terminal does not move.
[0166] The channel correlation distance may be a standard for
measuring whether basic channel characteristics change. In the
channel correlation distance, the basic channel characteristics
(such as a delay, an angle, and polarization) remain unchanged. If
the channel correlation distance is exceeded, the basic channel
characteristics (such as the delay, the angle, and the
polarization) change. After the channel correlation distance is
exceeded, the first angle power spectrum needs to be re-determined,
and an optimal high frequency beam may also change, and a high
frequency beam needs to be re-selected.
[0167] In this embodiment of this application, the channel
correlation distance may be determined based on a channel scenario
in which the terminal is currently located, and different channel
scenarios correspond to different channel correlation distances.
For example, Table 1 shows a correspondence between a channel
scenario and a channel correlation distance. As shown in Table 1,
using a rural area as an example, in a LOS scenario, the channel
correlation distance is 50 m, in an NLOS scenario, the channel
correlation distance is 60 m, and in an indoor to outdoor
(outdoor-to-indoor, O2I) scenario, the channel correlation distance
is 15 m.
[0168] If the moving distance of the terminal is less than or equal
to the channel correlation distance, it indicates that even if the
terminal moves, the channel characteristic of the low frequency
channel does not change greatly before and after the terminal
moves, and the first high frequency beam scanning range may still
be determined by using the previously determined first angular
power spectrum. On the contrary, if the moving distance of the
terminal is greater than the channel correlation distance, it
indicates that the channel characteristic of the low frequency
channel changes greatly after the terminal moves, and the
previously determined first angular power spectrum cannot reflect
the channel characteristic of the low frequency channel after
moving. In this case, the terminal needs to perform step 401 again
to re-determine the first angular power spectrum. Therefore, the
terminal obtains a new first high frequency beam scanning range
based on the re-determined first angular power spectrum, and scans
the new first high frequency beam scanning range for the high
frequency beam sent by the access network device.
TABLE-US-00001 TABLE 1 Channel scenario Rural area City Urban area
LOS NLOS O2I LOS NLOS O2I LOS NLOS O2I Indoor Channel correlation
50 60 15 12 15 15 40 50 15 10 distance (m)
[0169] For example, in this embodiment of this application, the
channel scenario in which the terminal is currently located may be
determined based on the first angular power spectrum. For example,
the terminal may calculate the peak-to-average ratio of the low
frequency channel based on the first angular power spectrum, and
determine the channel scenario in which the terminal is currently
located based on the PAR of the low frequency channel. When the
peak-to-average ratio is greater than or equal to 4, the terminal
determines that the channel scenario in which the terminal is
currently located is the LOS scenario. When the peak-to-average
ratio is less than 4 and is greater than or equal to 3, the
terminal determines that a current communication scenario in which
the terminal is located is a strong transmission scenario, for
example, a smooth glass or a metal surface. When the
peak-to-average ratio is less than 3 and is greater than or equal
to 2, the terminal determines that the communication scenario in
which the terminal is currently located is a scenario in which a
common reflection exists, for example, sparse vegetation. When the
peak-to-average ratio is less than 2 and is greater than or equal
to 1, the terminal determines that the communication scenario in
which the terminal is currently located is a scenario in which
common occlusion exists, for example, a scattering scenario. When
the peak-to-average ratio is less than 1, the terminal determines
that the current communication scenario in which the terminal is
located is a scenario in which dense vegetation and complete
occlusion exist.
[0170] It should be noted that, an example in which the terminal
scans for the high frequency beam sent by the access network device
is used for description. As an inverse process of downlink high
frequency beam management, the access network device may
alternatively scan for a high frequency beam sent by the terminal
in the manner shown in FIG. 4. For example, the terminal sends the
high frequency beam (or referred to as an uplink high frequency
beam) to the access network device. The access network device
calculates a peak-to-average ratio of a low frequency channel,
determines a high frequency beam scanning range based on the
peak-to-average ratio of the low frequency channel, and scans the
determined high frequency beam scanning range for the high
frequency beam sent by the terminal. Specifically, for a detailed
description of the process, refer to FIG. 7. Details are not
described again.
[0171] FIG. 7 is another beam selection method according to an
embodiment of this application. As shown in FIG. 7, the method may
include the following steps.
[0172] Step 701: An access network device determines an angular
power spectrum of a low frequency channel transmitted between the
access network device and a terminal.
[0173] For step 701, refer to step 401. For example, the low
frequency channel transmitted between the access network device and
the terminal is a low frequency channel (or referred to as an
uplink low frequency channel) sent by the terminal to the access
network device, and the access network device may determine a DOA
power spectrum of the low frequency channel. Alternatively, when
there is reciprocity between a channel sent by the terminal to the
access network device and a channel sent by the access network
device to the terminal, the low frequency channel transmitted
between the access network device and the terminal is a low
frequency channel (or referred to as a downlink low frequency
channel) sent by the access network device to the terminal, and the
access network device may determine a DOD power spectrum of the low
frequency channel. In this way, a high frequency beam (or referred
to as an uplink high frequency beam) sent by the terminal to the
access network device may be determined by using a channel
characteristic of the downlink low frequency channel.
[0174] Specifically, for a detailed description of step 701, refer
to step 401. Details are not described again.
[0175] Step 702: The access network device determines a third high
frequency beam scanning range based on the angular power spectrum
of the low frequency channel determined in step 701.
[0176] For step 702, refer to step 402. For example, the access
network device may calculate a peak-to-average ratio of the low
frequency channel based on the determined angular power spectrum,
and determine the third high frequency beam scanning range based on
the peak-to-average ratio of the low frequency channel and a
correspondence between the peak-to-average ratio and a high
frequency beam region range.
[0177] For a correspondence between the peak-to-average ratio and
the high frequency beam region range, and a detailed process in
which the access network device determines the third high frequency
beam scanning range, refer to step 402. Details are not described
again.
[0178] Step 703: The access network device scans the third high
frequency beam scanning range determined in step 702 for the high
frequency beam sent by the terminal.
[0179] For step 703, refer to step 403. Details are not described
again.
[0180] Based on the method shown in FIG. 7, when scanning the high
frequency beam sent by the terminal, the access network device may
determine, based on the angular power spectrum of the low frequency
channel, the third high frequency beam scanning range, and scan the
third high frequency beam scanning range for the high frequency
beam sent by the terminal. In this way, the access network device
may scan a specific range for the high frequency beam, and does not
need to scan a large range for the high frequency beam by using
three phases P1 to P3 as in the conventional technology. Compared
with the conventional technology, the method provided in FIG. 7
reduces a scanning time. In addition, signaling interaction with
the terminal does not need to be performed for a plurality of
times, thereby reducing signaling overheads.
[0181] The method shown in FIG. 4 is described below by using an
example in which the terminal determines a high frequency beam
scanning range based on an angular power spectrum of a low
frequency channel, and scans the determined high frequency beam
scanning range for a high frequency beam sent by the access network
device.
[0182] FIG. 8 is a beam selection method according to an embodiment
of this application. As shown in FIG. 8, the method may include the
following steps.
[0183] Step 801: A terminal receives a low frequency channel sent
by an access network device, and determines to obtain a DOA power
spectrum of the low frequency channel; or a terminal sends a low
frequency channel to an access network device, to determine a DOD
power spectrum of the low frequency channel.
[0184] For step 801, refer to step 401. Details are not described
again.
[0185] For a manner in which the access network device sends the
high frequency beam to the terminal, refer to step 403. Details are
not described again.
[0186] Step 802: The terminal determines whether the terminal
rotates. If the terminal rotates, step 803 is performed. If the
terminal does not rotate, step 804 is performed.
[0187] For a manner in which the terminal determines whether the
terminal rotates, refer to the description in the embodiment shown
in FIG. 4. Details are not described again.
[0188] Step 803: The terminal corrects the DOA power spectrum or
the DOD power spectrum of the low frequency channel based on a
rotation angle of the terminal.
[0189] For a manner in which the terminal corrects the DOA power
spectrum or the DOD power spectrum of the low frequency channel,
refer to the third embodiment of the method shown in FIG. 4.
Details are not described again.
[0190] Step 804: The terminal determines, based on the DOA power
spectrum or the DOD power spectrum of the low frequency channel, a
channel scenario in which the terminal is currently located.
[0191] The channel scenario may include a LOS scenario, an NLOS
scenario, an 021 scenario, and the like.
[0192] Specifically, for a detailed process in which the terminal
determines the channel scenario based on the DOA power spectrum or
the DOD power spectrum of the low frequency channel, refer to the
fourth embodiment of the method shown in FIG. 4. Details are not
described again.
[0193] Step 805: The terminal determines a high frequency beam
scanning range based on the DOA power spectrum or the DOD power
spectrum of the low frequency channel.
[0194] For step 805, refer to step 402. Details are not described
again.
[0195] Step 806: The terminal selects a candidate beam based on the
DOA power spectrum or the DOD power spectrum of the low frequency
channel.
[0196] For an execution process of step 806, refer to the
description in the first embodiment of the method shown in FIG. 4.
Details are not described again.
[0197] Step 807: The access network device sends the high frequency
beam to the terminal.
[0198] Step 808: The terminal determines whether the terminal
translates. If the terminal translates, step 809 is performed. If
the terminal does not translate, step 810 is performed.
[0199] For a manner in which the terminal determines whether the
terminal translates, refer to the description in the embodiment
shown in FIG. 4. Details are not described again.
[0200] Step 809: Determine whether a translation distance of the
terminal is greater than a channel correlation distance. If the
translation distance of the terminal is greater than the channel
correlation distance, step 801 is performed again; otherwise, if
the translation distance of the terminal is less than or equal to
the channel correlation distance, step 810 is performed.
[0201] The terminal may determine the channel correlation distance
based on the channel scenario in which the terminal is currently
located and that is determined in step 804.
[0202] Step 810: The terminal scans the high frequency beam
scanning range determined in step 805 for the high frequency beam
sent by the access network device.
[0203] Further optionally, if the terminal fails to scan the
determined high frequency beam scanning range for the high
frequency beam sent by the access network device, or successfully
scans, in the determined high frequency beam scanning range, the
high frequency beam sent by the access network device, but fails to
receive data, the terminal may communicate with the access network
device on the candidate beam selected in step 806.
[0204] Based on the method shown in FIG. 8, when scanning for the
high frequency beam delivered by the access network device, the
terminal may determine whether the terminal rotates, and if the
terminal rotates, correct the angular power spectrum of the low
frequency channel, thereby improving accuracy of the angular power
spectrum of the low frequency channel and ensuring accuracy of the
determined high frequency beam scanning range. Subsequently, before
scanning the high frequency beam in the high frequency beam
scanning range, the terminal determines whether the terminal
translates, and determines, based on a translation status of the
terminal, whether to scan the previously calculated high frequency
beam scanning range for the high frequency beam or to recalculate
the high frequency beam scanning range, so as to improve accuracy
of high frequency beam scanning.
[0205] The foregoing mainly describes the solutions provided in the
embodiments of this application from a perspective of interaction
between nodes. It may be understood that, to implement the
foregoing functions, the nodes such as the access network device
and the terminal include corresponding hardware structures and/or
software modules for performing the functions. A person skilled in
the art should easily be aware that, in combination with the
examples described in the embodiments disclosed in this
specification, algorithm steps may be implemented by hardware or a
combination of hardware and computer software. Whether a function
is performed by hardware or hardware driven by computer software
depends on particular applications and design constraint conditions
of the technical solutions. A person skilled in the art may use
different methods to implement the described functions for each
particular application, but it should not be considered that the
implementation goes beyond the scope of this application.
[0206] In the embodiments of this application, functional modules
of the access network device and the terminal may be divided based
on the foregoing method examples. For example, each functional
module may be obtained through division based on each corresponding
function, or two or more functions may be integrated into one
processing module. The integrated module may be implemented in a
form of hardware, or may be implemented in a form of a software
functional module. It should be noted that, in the embodiments of
this application, module division is an example, and is merely
logical function division. In actual implementation, another
division manner may be used.
[0207] FIG. 9 is a schematic structural diagram of a communications
apparatus 90 according to an embodiment of this application. The
communications apparatus in this embodiment may be a terminal, a
chip in a terminal, or a system-on-a-chip. The communications
apparatus 90 may be configured to perform a function of the
terminal in the foregoing method embodiments. In an implementation,
as shown in FIG. 9, the communications apparatus 90 may include a
determining unit 901 and a scanning unit 902.
[0208] The determining unit 901 is configured to determine a first
angular power spectrum of a low frequency channel transmitted
between a terminal and an access network device. For example, the
determining unit 901 may be configured to support the
communications apparatus 90 in performing step 401 and step
801.
[0209] The determining unit 901 is further configured to determine
a first high frequency beam scanning range based on the first
angular power spectrum. For example, the determining unit 901 may
be further configured to support the communications apparatus 90 in
performing step 402 and step 804.
[0210] The scanning unit 902 is configured to scan the determined
first high frequency beam scanning range for a high frequency beam
sent by the access network device. For example, the scanning unit
902 may be configured to support the communications apparatus 90 in
performing step 403 and step 810.
[0211] Specifically, the communications apparatus 90 provided in
this embodiment of this application may perform actions of the
terminal in the method embodiment corresponding to FIG. 4 or FIG.
8. Implementation principles and technical effects thereof are
similar. Details are not described herein again.
[0212] In another possible implementation, the communications
apparatus 90 shown in FIG. 9 may include a processing module and a
communications module. The processing module may integrate
functions of the determining unit 901 and the scanning unit 902.
The processing module is configured to support the communications
apparatus 90 in performing step 401 to step 403 and an action of
the terminal in the method shown in FIG. 8, and control and
management of the action of the communications apparatus 90. The
communications module is configured to support the communications
apparatus 90 to communicate with another network entity, for
example, communicate with the access network device. Further, the
communications apparatus 90 shown in FIG. 9 further includes a
storage module, configured to store program code and data of the
communications apparatus 90.
[0213] The processing module may be a processor or a controller.
The processing unit may implement or execute various example
logical blocks, modules, and circuits described with reference to
content disclosed in this application. Alternatively, the processor
may be a combination of processors implementing a computing
function, for example, a combination of one or more
microprocessors, or a combination of a DSP and a microprocessor.
The communications module may be a transceiver circuit, a
communications interface, or the like. The storage module may be a
memory. When the processing module is the processor, the
communications module is the communications interface, and the
storage module is the memory, the communications apparatus 90 shown
in FIG. 9 may be the communications apparatus shown in FIG. 3.
[0214] FIG. 10 is a schematic structural diagram of a beam
selection system according to an embodiment of this application. As
shown in FIG. 10, the system may include a terminal 100 and an
access network device.
[0215] A function of the terminal 100 is the same as that of the
communications apparatus 90 shown in FIG. 9. For example, the
terminal 100 may be configured to: determine a first angular power
spectrum of a low frequency channel transmitted between the
terminal and the access network device, determine a first high
frequency beam scanning range based on the first angular power
spectrum, and scan the first high frequency beam scanning range for
a high frequency beam sent by the access network device.
[0216] Specifically, the communications system provided in the
embodiments of this application may perform the method embodiments
corresponding to FIG. 3 to FIG. 6. Implementation principles and
technical effects thereof are similar, and details are not
described again.
[0217] The foregoing description about the implementations allows a
person skilled in the art to clearly understand that, for the
purpose of convenient and brief description, division into only the
foregoing functional modules is used as an example for description.
During actual application, the foregoing functions can be allocated
to different functional modules for implementation as required. In
other words, an inner structure of an apparatus is divided into
different functional modules to implement all or some of the
functions described above.
[0218] In the several embodiments provided in this application, it
should be understood that the disclosed apparatus and method may be
implemented in other manners. For example, the described apparatus
embodiments are merely examples. For example, division into the
modules or units is merely logical function division. There may be
another division manner in actual implementation. For example, a
plurality of units or components may be combined or may be
integrated into another apparatus, or some features may be ignored
or not be performed. In addition, the displayed or discussed mutual
coupling or direct coupling or communication connection may be
implemented by using some interfaces. The indirect coupling or
communication connection between the apparatuses or units may be
implemented in electrical, mechanical, or another form.
[0219] The units described as separate components may or may not be
physically separate, and components displayed as units may be one
or more physical units, that is, may be located in one place, or
may be distributed on a plurality of different places. Some or all
of the units may be selected based on actual requirements to
achieve the objectives of the solutions in the embodiments.
[0220] In addition, functional units in the embodiments of this
application may be integrated into one processing unit, or each of
the units may exist alone physically, or two or more units are
integrated into one unit. The integrated unit may be implemented in
a form of hardware, or may be implemented in a form of a software
functional unit.
[0221] When the integrated unit is implemented in the form of a
software functional unit and sold or used as an independent
product, the integrated unit may be stored in a readable storage
medium. Based on such an understanding, the technical solutions of
the embodiments of this application essentially, or the part
contributing to the conventional technology, or all or some of the
technical solutions may be implemented in the form of a software
product. The software product is stored in a storage medium and
includes several instructions for instructing a device (which may
be a single-chip microcomputer, a chip, or the like) or a processor
(processor) to perform all or some of the steps of the method
described in the embodiments of this application.
[0222] The foregoing storage medium includes: any medium that can
store program code, such as a USB flash drive, a removable hard
disk, a ROM, a RAM, a magnetic disk, or an optical disc.
[0223] The foregoing descriptions are merely specific
implementations of this application, but are not intended to limit
the protection scope of this application. Any variation or
replacement within the technical scope disclosed in this
application shall fall within the protection scope of this
application. Therefore, the protection scope of this application
shall be subject to the protection scope of the claims.
* * * * *